Association between the Circadian Clock and the Tumor Microenvironment in Breast Cancer.

Breast cancer (BC) is the most common cancer in women. Globally, the incidence of BC surpassed lung cancer for the first time in 2020, and it is highly heterogeneous. The tumor microenvironment (TME) of BC consists of blood vessels, fibroblasts, signaling molecules, immune cells, and extracellular matrix. Numerous studies have provided considerable evidence regarding the association between the circadian rhythm (CR) and human diseases. The CR induces remodeling of the TME cells and their components by disturbing the cellular metabolism, altering gene expression, and aberrantly activating signaling pathways. In this review we present the recent updates on the CR genes and their molecular mechanisms and signaling pathways. In addition, we present the mutations and single nucleotide polymorphisms in the CR genes and the CR pathways in BC biology and the management of the CR in patients with BC. The association between the CR and the TME in BC is also explored.